Electromagnetic switching device



May 3, 1938. F. A. ZUPA ELECTROMAGNETIC SWITCHING DEVICE Filed Oct. 6, 1934 FIG.

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/N VE N TOR F. A. ZUPA AT TORNEK Patented May 3, i938 "PATENT OFFICE ELECTROMAGNETIC SWITCHING DEVICE Frank A. Zupa, New York,

Telephone Laboratories,

N. Y., asslgnor to Bell Incorporated, New

York, N. Y., a corporation of New York Application October 6,

3 Claims.

This invention relates to electric switching devices and particularly to electromagnetic relays.

In electrical systems generally, and in telephone systems particularly, the electromagnetic relay plays an important part and is one of the most extensively employed switching devices in communication systems. I

.To insure satisfactory functioning of the circuits'of a telephone system and to guard against interruption of service, it is necessary that the relays employed in such systems be so designed as tooperate at maximum emciency at all times and be so constructed as to permit adjustment to be made in the field without undue disturbance to the relay as a whole. Two of the many elements which constitute a relay structure and upon a satisfactory design of whichdepends, to a major extent, the efliciency of a relay, are the contact sprin s and the magnetic circuit.

In contributing to the overall efficiency of a relay it is necessary that the contact spring be so designed as to be sufficiently stiff for tensioning purposes and to insure its returnto normal after actuation by the armature and at the same time maintain a relative flexibility at its contact end. The magnetic circuit should be of such a nature as to produce a maximum air-gap flux for a given value of operating current; in other words, the leakage flux or that portion of the 3 total core flux which does not cross the armature and consequently can not be utilized for producing traction should be reduced to a minimum.

It is the object of this invention to improve the design of electromagnetic relays so as to provide a relay of maximum eiiiciency and one whose parts may be readily adjusted.

This object is attained, in accordance with a feature of the invention, by the provision'of a relay contact spring which has a greater stiffness throughout the major portion of its length than the contact carrying portion thereof and which is substantially chatterless.

Another feature of the invention resides in a 5 particular design of armature back-stop which is so constructed and which cooperates with the relay core and armature in such a manner as-to introduce no added or unnecessary leakage of the magnetic flux reaching the relay pole gap.

A further feature of the invention resides in a particular design of armature support which permits armature adjustments to be made without disturbance to the relay structure as a whole and which, while sufficiently flexible to permit the nor- 15 mal functioning of the armature, is adequately 1934, Serial No. 747,125

rigid to resist any forces which tend to move the armature abnormally.

These and other features of the invention which contribute to the overall efllciency of the relay will be readily understood from the following detailed description made with reference to the accompanying drawing in which:

Figs. 1, 2, 3 .and 4 show, View, a side elevation, a bottom plan view and a front end view of a relayembodying the features of the invention; and

Fig. 5 shows a fragmentary perspective view of the contact springs utilized in the relay of this invention.

The relay core I0 is substantially cylindrical throughout its length and on an intermediate portion thereof front portion of the core ill or that portion immediately below the front cross-bar of the armature is flattened to provide a pole face of suitable area.

'An L-shaped bracket comprising portions l2 and I3 is welded to the rear portion of the core Ill. The depending portion l3 (as seen in Fig. 2). of the bracket serves as means for mounting the relay on a relay rack, the portion l2, extending the entire width of the relay, constituting a support for the spring pile-ups which are located on either side of the relay and secured to the bracket portion i2 by means of screws l4 and I5.

Interposed betweenthe upper spring pile-ups and the bracket portion I2 is secured, also by means of the screws l4 and l5,-a U-shaped bracket It provided with the integral upturned lugs H which extend in a direction at right angles to the longitudinal axis of thecore I0.- On the rear cross-bar of armature l8 there is clamped by means of a clamping member l9 and the rivets 20, a reed 2| which extends substantially across the entire length of the rear cross-bar of the armature. The reed 2|. is provided with integral right-angular projections 22, which are in alignment with the projections ll of the bracket 15' and which are secured thereto by means of screws 23 which pass through oblong holes in the reed elements 22. By virtue of the contour of the holes in the reed portions 22, the armature may be raised or lowered with respect to the core ill by merely loosening the screws 23, adjusting the armature to the desired level and then tightening the screws 23. A longitudinal adjustment of the armature may also be made by loosening the screws l4, l5, moving the bracket it forward or backward, in accordance with the required adjustment, and then tightening the screws l4, l5,

respectively, a top plan supports the relay coil II. The

ing separated by an insulator in accordance withusual practice, and are secured to the bracket portion II by means of screws H and I! as proviousiy mentioned. The passive or stationary contact spring 25 is relatively thick and carries on its free end two contact elements "disposed at right angles to the longitudinal axis' oi the spring; A lateral projection 21 on the spring 25 abuts against a projection, such as 28, on the front spool-head 29, the projections 28 serving as spacers for the springs 25 which are normally tensioned against the spool-head projections.

The companion active or movable contact spring 30 is made up of two relatively thin spring elements or blades 3! and 32 spot-welded together, the element 32 being of greater length than that of the element 3|. The portion of element 32 which extends beyond the end of ele ment 3| constitutes the contact carrying portion of the spring and is bifurcated to provide a split spring, each portion affected by the bifurcation carrying a contact element 33 disposed at 'right angles to thetransverse axis of the spring 30. The split spring and its associated contacts constitute a parallel contact arrangement which minimizes the danger of faulty contact. v

The particular construction of spring 30 re'- suits in a contact spring having a greater stiffness throughout the major portion of its length than the contact carrying portion thereof, thereby insuring the desirable characteristic of flexibility at the contact portion'while maintaining the necessary tension for returning the spring to normal after its actuation together with the actuating armature. It is also to be noted that the thickness of the spring 30 at any point on its length is no greater than the combined thicknesses of the two blades 31 and 32. This spring construction, therefore, not only provides the necessary tension for controlling its return movement and the desired flexibility at the contact bearing end, but

does so without sacrificing any space allotted to the contact springs.

The back-stop utilized in this construction comprises an L-shaped' pin 35 having one end and to provide the necessary armature bearing surface for the nut. This type of construction permits the front edges 01' the core II and armsfture II to be in substantial alignment thereby reducing the leakage paths which are common to arrangments heretofore employed in which the core, to provide mounting space for the backst p. extended beyond the front end of the armature; This arrangement reduces leakage flux to a minimum "and permits substantially all of the core flux to cross the armature air-gap and therefore to be utilized for producing traction.

The front end of the core II may be bored to permit the insertion of the pin 3| which may then be staked into position as generally indicated by the holes 31 (Fig. 3).

What is claimed is:

1." In an electromagnetic switching device, relatively movable armature and core members whose forward ends are in substantial alignment and means for regulating the relative movement of said members, said means comprising a pin protruding longitudinally from the forward end of said core and extending at right angles thereto beyond the forward end of said armature and a nut adiustably carried by said pin in operative association with said armature.

,2. In an electromagnetic switching device, an armature and means for mounting said armature on saiddevice, said means comprising a reed clamped to said armature and having two up j" turned flanges, an adjustable bracket mounted on said device and having two upturned flanges in alignment with the flanges of said reed and means for clamping said aligned flanges together.

3. In an electromagnetic switching device, an armature and means for mounting said armature on said device, said means comprising av reed clamped to said armature and having two upturned flanges, a bracket adiustably mounted on said device and having two upturned flanges in alignment with the flanges of said reed, said reed flanges being adjustable relative to said bracket flanges and'means for clamping said reed to'said mm: A. ZUPA. 

